Objective To investigate the clinical effect of retrograde interlocking intramedullary nail for supracondylar femur fractures. Methods The retrograde i nterlocking intramedullary nails were used for 50 cases of fractures of the supr acondylar femur.The patients were directed to taking function exercise 72h after operation. Result 50 cases were followed up for 4~24 months,10 months on avera ge.The time of bone healing was 3~8 months.The knee function recovered well wit h excellent result rate of 96%. Conclusion Retrograde interlocking intramedullar y nails can ensure intrinsic stability with simple procedures.Function exercise can be used soon after operation to ensure quick fractures healing and have fewe r complications.It is an optimal measures for fractures of supracondylar femur.